the level of horse DNA in its Buitoni Beef Ravioli and Beef Tortellini meals was above the 1 percent threshold that the U.K. Food Safety Agency uses to indicate likely adulteration or gross negligence.

Horse meat is more commonly consumed in Europe than here in the US. The issue isn't that there was horse meat in the food supply, the issue is that it was mis-labeled as beef.

If you set the threshold at zero, then meat processing plants that handle horse meat would not be able to also handle beef.

That said, 1% does seem a little high to me; but zero is too low, for the reason stated above.

Edit: They probably chose 1% because it is A) low enough to catch intentional cases of fraud; B) high enough that incidental/accidental low-level cross-contamination in plants that handle multiple types of meat won't constitute a violation; and C) a nice round number that even mathematically challenged legislators, bureaucrats, and members of the public can understand.

The years just pass like trains. I wave, but they don't slow down.-- Steven Wilson

One would hope that the machines are getting cleaned well enough between batches to get the contamination level below 1% regardless of this rule. While 2% is still probably below the level that would indicate willful fraud, it definitely shows a lack of attention to cleanliness.

The years just pass like trains. I wave, but they don't slow down.-- Steven Wilson

Yes, I realize that. My point was that the 1% threshold is probably there so that accidental low-level cross-contamination isn't counted as fraud (or product mislabeling, or whatever they're calling it). They've presumably got separate rules regarding general cleanliness of the facilities and equipment.

The years just pass like trains. I wave, but they don't slow down.-- Steven Wilson

If an industial mincer grinds up 50 metric tonnes of beef a day and the end result contains 1% horse, then that means there was half a tonne of horse "stuck in the machine"

HALF A TONNE.

over 1% horse means that criminals in the EU have been forging paperwork and selling horsemeat as beef, that is all.

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Take your meat-packing plant, and run a batch of horsemeat through it. Do a pretty good job cleaning, but you might miss a morsel or two. Run a batch of beef through it. The first bit through might have up to 1% horsemeat contamination (assuming things are kosher, as it were), but the last bits of cow might not have detectable levels of horse. Clean and run a batch of horse through again & you'll see cow contamination in the first bits.

One assumes the regulatory agency's sampling methods are reasonably random and that they'd look askance if a big batch of beef had similar levels of contamination throughout.

If you made the threshold 0% on pretty much anything that is considered toxic/lethal etc. you'd basically stop every single industry in the world from doing anything. Sure some things are able to be kept to below ppb, ppm, etc. levels, but it still means that turning that ppb no. into 0 is effectively impossible because almost everything is contaminated with some horse meat, some mercury, some cocaine etc.